The present invention relates to the mechanical clamping arts. It finds particular application in conjunction with securing assembly parts in a factory or mill setting and will be described with particular reference thereto. It will be appreciated, however, that the invention is also applicable to other settings and is not limited to the aforementioned application.
Mechanical clamps have a very wide range of applications in the manufacturing industry. Generally, application of clamping devices can be divided into three main classes. First, clamps are used to secure parts that are being worked upon, such as machined, formed, stamped, etc. Second, clamps are used to clamp various machine parts into a locked position within a manufacturing tool. Third, clamps are used to position machine tool components for operations they are meant to perform. Some examples of these devices that are generally known as clamps are machine vises, fixture clamps, lathe chucks, tool holders, drill feed units, electrical discharge machining (EDM) electrode feed units, weld wire feed units, and others.
One method of clamping which can be generically applied to any of the aforementioned devices is mechanical clamping. These devices include screw clamps, over center cam devices, and wedges. They are manually applied with levers or tools such as socket wrenches or air guns. The manual opening and closing of these clamps creates direct labor and extra mill downtime. Additionally, such workers are at risk for repetitive task related injuries.
Hydraulic systems are frequently used to operate clamps. Hydraulic systems have the benefits of being remotely operated, and having very high clamping pressures. However, hydraulic systems have a relatively high failure rate. Leaks, damaged o-rings, fittings, and hoses create situations of long down-times and high repair costs. Leaking hydraulic fluid can be hazardous to those who come into contact with it, making clean-up necessary, and dangerous if not handled properly. Oil leaks from hydraulic systems can contaminate cutting fluids, causing potential health problems when the fluids are vaporized by cutting blades. Moreover, hydraulic systems experience wear when torn down and built up, such as when arranging a shop to machine different goods. If a machine shop changes its output product often, the hardware degrades more quickly.
In hydraulic systems, the supply hoses are at pressure when the system is actuated. These stresses on the hoses often cause them to warp and bend in unwanted directions. In an automated mill, such a situation can present a catastrophic problem. If a hose becomes warped such that it gets in the path of an automated mill part, the automated part can tear the hydraulic hose causing loss of clamping force and leakage of hydraulic fluid. Both results present dangerous situations to mill workers.
Pneumatic devices are also known in the art as an option for operating clamps. Pneumatic systems are beneficial because production is not halted to repair minor leaks. Typically, pneumatic systems run in shops constantly hiss, and spit, indicative of damaged o-rings and minor leaks. However, pneumatic systems also have their share of setbacks. Noise levels generated by pneumatic systems often exceed OSHA limits. Typical pneumatic systems are low pressure systems not suitable for machining. Pneumatic clamps, as a result can have a compressibility that is undesirable. Moreover, pneumatic systems can release oil-laden air, which is a potential health risk.
Electric motors are also known, but are relatively poor for generating a static, clamping force. They are relatively massive, require extensive electronic packages, and are costly to operate.
The present invention provides a new and improved method and apparatus which overcomes the above-referenced problems and others.
In accordance with one aspect of the present invention, a mechanical actuating system is provided. A housing defines a polymer chamber, piston ports, and thermal medium ports. A volume of polymer is contained within the polymer chamber. A fluid passage extends between the ports. Pistons are disposed in the piston ports. Heat transfer fluid flows through the passage.
In accordance with another aspect of the present invention, a mechanical actuation system is provided. A liquid source provides warmer and cooler liquid to a plurality of actuators. Each actuator includes a housing body with fluid ports and a liquid flow path, an interior chamber, and a piston bore in fluid communication with the chamber. A piston is in the chamber. A phase change material is in the chamber, which expands and contracts as it changes phases. A controller controls the liquid source.
In accordance with another aspect of the present invention, a method of actuating is provided. A polymer is disposed in a sealed polymer chamber. The temperature of the polymer chamber is varied causing the polymer to expand and contract forcing a piston to stroke.
In accordance with another aspect of the present invention, a method of controlling a plurality of pistons in provided. Liquid is warmed and circulated to melt the polymer, and it is cooled and circulated to freeze the polymer.
According to another aspect of the present invention, a mechanical actuating device is provided. An outer housing defines a sealed polymer chamber, wherein is located an expansible polymer. A piston responds to expansion of the polymer. The polymer expands in response to a thermal carrier transferring heat into the polymer. A spring applies an opposing force to the force applied on the piston by the polymer.
According to another aspect of the present invention, a clamping system is provided. A mechanical actuator includes a piston received in a sliding relationship in a piston bore, a volume of polymer in a polymer chamber, and a heat transfer conduit through which heat transfer fluid flows, adding and removing heat from the polymer. The actuator is attached to a base. The base includes a clamping surface opposite the piston, and a means of securing the actuator in position. The base is secured to a stationary surface. A power supply supplies heat transfer fluid to the actuator. The power supply includes hot, cool, and warm fluid reservoirs, each reservoir holding a volume of the heat transfer fluid at different temperatures. The hot reservoir holds fluid that will melt the polymer, the cool reservoir holds fluid that will solidify he polymer, and the warm reservoir holds fluid that will keep the polymer melted once it is in a liquid state. The power supply also includes a pump for moving the transfer fluid.
According to another aspect of the present invention, a method of automated machining is provided. A mechanical actuator is secured to a base by an animated inorganic entity. Supply lines are attached to the actuator utilizing quick-connect fittings. A part is clamped between an extended piston of the actuator and a portion of the base by passing warmer heat transfer fluid through the actuator. Work is done on the clamped part by a second animated inorganic entity. The part is unclamped by passing cooler heat transfer fluid through the actuator.
One advantage of the present invention resides in hydraulic strength force clamping levels.
Another advantage resides in the elimination of possible oil discharge.
Another advantage is the circulation of only biologically safe fluids.
Another advantage resides in the elimination of high pressure circulation lines.
Another advantage resides in the reduction of the possibility of damage to supply lines by automated mills.
Another advantage resides in quick connection and disconnection of circulating fluids.
Another advantage resides in reduced factory downtime.
Another advantage resides in the enablement of arrays of multiple clamps.
Another advantage resides in user controllable clamping force levels.
Another advantage resides in more force for warmer temperatures.
Another advantage resides in less force for cooler temperatures.
Yet another advantage resides in the reduction of manual labor.
Still further benefits and advantages of the present invention will become apparent to those skilled in the art upon a reading and understanding of the preferred embodiments.